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LibC+LibPthread: Make sure TLS keys are destroyed after everything else

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This ensures that __thread variables can be used when global destructors
are being invoked.
This commit is contained in:
Gunnar Beutner 2021-04-17 18:37:00 +02:00 committed by Andreas Kling
parent 6eedb570a2
commit 4075b306f8
Notes: sideshowbarker 2024-07-18 19:29:07 +09:00 
Author: https://github.com/gunnarbeutner
Commit: https://github.com/SerenityOS/serenity/commit/4075b306f8d
Pull-request: https://github.com/SerenityOS/serenity/pull/6417
3 changed files with 18 additions and 12 deletions
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7
Userland/Libraries/LibC/stdlib.cpp
View file

@ -31,6 +31,7 @@
#include <AK/Types.h>
#include <AK/Utf8View.h>
#include <LibELF/AuxiliaryVector.h>
#include <LibPthread/pthread.h>
#include <alloca.h>
#include <assert.h>
#include <ctype.h>
@ -48,6 +49,8 @@
#include <syscall.h>
#include <unistd.h>
void (*__libc_pthread_key_destroy_for_current_thread)() = nullptr;
static void strtons(const char* str, char** endptr)
{
assert(endptr);
@ -224,6 +227,10 @@ void exit(int status)
_fini();
fflush(stdout);
fflush(stderr);
if (__libc_pthread_key_destroy_for_current_thread)
__libc_pthread_key_destroy_for_current_thread();
_exit(status);
}

21
Userland/Libraries/LibPthread/pthread.cpp
View file

@ -46,25 +46,17 @@
namespace {
using PthreadAttrImpl = Syscall::SC_create_thread_params;
struct KeyDestroyer {
~KeyDestroyer() { destroy_for_current_thread(); }
static void destroy_for_current_thread();
};
} // end anonymous namespace
constexpr size_t required_stack_alignment = 4 * MiB;
constexpr size_t highest_reasonable_guard_size = 32 * PAGE_SIZE;
constexpr size_t highest_reasonable_stack_size = 8 * MiB; // That's the default in Ubuntu?
// Create an RAII object with a global destructor to destroy pthread keys for the main thread.
// Impact of this: Any global object that wants to do something with pthread_getspecific
// in its destructor from the main thread might be in for a nasty surprise.
static KeyDestroyer s_key_destroyer;
#define __RETURN_PTHREAD_ERROR(rc) \
return ((rc) < 0 ? -(rc) : 0)
extern void (*__libc_pthread_key_destroy_for_current_thread)();
extern "C" {
static void* pthread_create_helper(void* (*routine)(void*), void* argument)
@ -105,7 +97,7 @@ static int create_thread(pthread_t* thread, void* (*entry)(void*), void* argumen
[[noreturn]] static void exit_thread(void* code)
{
KeyDestroyer::destroy_for_current_thread();
__pthread_key_destroy_for_current_thread();
syscall(SC_exit_thread, code);
VERIFY_NOT_REACHED();
}
@ -592,7 +584,12 @@ int pthread_setspecific(pthread_key_t key, const void* value)
return 0;
}
void KeyDestroyer::destroy_for_current_thread()
[[gnu::constructor]] static void set_libc_key_destructor()
{
__libc_pthread_key_destroy_for_current_thread = __pthread_key_destroy_for_current_thread;
}
void __pthread_key_destroy_for_current_thread()
{
// This function will either be called during exit_thread, for a pthread, or
// during global program shutdown for the main thread.

2
Userland/Libraries/LibPthread/pthread.h
View file

@ -146,4 +146,6 @@ int pthread_rwlockattr_setpshared(pthread_rwlockattr_t*, int);
int pthread_atfork(void (*prepare)(void), void (*parent)(void), void (*child)(void));
void __pthread_key_destroy_for_current_thread();
__END_DECLS